Electronics systems, such as communication systems, information systems, entertainment systems, radar systems, infrared sensor systems, laser tracking systems, or directed energy systems, whether commercial, ground-based, mobile, airborne, shipboard, or spacecraft systems, require DC power to operate the electronics. High frequency (≧50 kHz) switching power converters are the power conversion equipment of choice to provide the DC power for the electronics, being much more efficient, smaller, and lighter than linear power supplies.
Unfortunately, switch mode power conversion is not without its drawbacks. In some applications electronics systems require primary to secondary isolation or may have other requirements that may require the use of transformers. Common mode current capacitively coupled through the switching power converter's power transformer from primary to secondary may be a major source of noise in electronics systems using a switching power converter. Common mode current capacitively coupled from a wound magnetic assembly to chassis may be another major source of noise in electronics systems using a switching power converter.
If uncontrolled, common mode current may manifest itself as differential noise due to impedance mismatches between signal and signal return. This noise can wreak havoc in the electronics system by, for example, generation of false signals and false triggering of digital logic. Such noise has been known to prevent successful communication between electronics systems, rendering the electronics systems inoperable.